The Mosteiro de Castro de Avelas is a small but distinctive monastery site outside Braganca. Its surviving Romanesque apses are built in brick, a material choice that immediately sets it apart from the granite churches more typical of northern Portugal.
It is a short detour rather than a major excursion, but a good one if you are interested in medieval architecture. The quiet rural setting also gives a useful break from Braganca's citadel and museum circuit.